Bob

Bob is a Fish shell plugin that keeps your command history tidy by automatically removing mistyped or otherwise unwanted commands.

This project is based on Sponge (originally by Andrei Borisov) and is released under the MIT License.

This version includes bug fixes and a substantial refactor to reduce global state, improve Fisher-based uninstallability, and fixes a history-search bug present in the original Sponge implementation.

🛠️ Installation

Install with Fisher:

fisher install enklht/bob

🤔 What it does

Use your shell normally; Bob runs in the background and keeps your history clean. It:

• Automatically removes failed commands after a short delay (unless the command already exists in history and is allowed).
• Keeps a small buffer of recent commands (default: 2) so you can quickly re-run or correct mistakes.
• Lets you add custom keep (whitelist) and drop (blacklist) rules.

📝 Note 📝 :
Bob does not remove commands that failed before installation. If you want to clear all previous history, you can reset it with history clear (this clears the entire history regardless of exit status. Be careful).

⚙️ Configuration

All configuration is done via Fish variables. You can place these in your config.fish or set them interactively.

Delay before purging

Bob keeps recent commands for a short delay so you can still access them via history. Adjust the delay with:

set bob_delay 5

To keep the session history intact until you exit the shell:

set bob_purge_only_on_exit true

Built-in rules

Bob ships with keep (whitelist) and drop (blacklist) rules by default.

Rule order and defaults:

• Keep rules (whitelist) are evaluated first.
• If no keep rule matches, drop rules (blacklist) are evaluated next.
• If no rule matches, the command is kept.

Defualt keep rules (whitelist):

• bob_keep_in_history: keeps commands that already existed in history (configurable).
• bob_keep_regex: keeps commands that match one or more regex patterns.

Default drop rules (blacklist):

• bob_drop_failed: drops commands with exit codes considered unsuccessful.
• bob_drop_regex: drops commands that match one or more regex patterns.

Configuration examples

• Settings for bob_drop_failed:

# Which exit codes are treated as successful by bob_drop_failed
# default: 0
set bob_successful_exit_codes 0 127

• Settings for bob_keep_in_history

# If false, bob_keep_in_history will not keep commands that already exist in history.
# default: true
set bob_allow_previously_successful false

• Settings for bob_keep_regex and bob_drop_regex:

# Regex patterns used by bob_keep_regex; any matching command will be kept.
# default: empty
set bob_regex_whitelist '(?:\d{1,3}\.){3}\d{1,3}'

# Regex patterns used by bob_drop_regex; any matching command will be dropped.
# default: empty
set bob_regex_blacklist '(?:^|\s)rm\s+-rf\s+/tmp'

Custom rules

You can add custom rules. A rule is a Fish function that receives two positional arguments:

1. command: the exact command string entered
2. exit_code: the command's exit status

Return exit status 0 when the rule matches, or a non-zero value when it does not. You can define your custom rule in config.fish or in the functions directory as a standalone function.

Register your keep rules by appending their names to bob_keep_rules:

set --append bob_keep_rules your_awesome_rule

Register your drop rules by appending their names to bob_drop_rules:

set --append bob_drop_rules your_awesome_rule

Example custom rule

This example demonstrates a custom drop rule that removes commands when the current working directory is under /tmp. A rule should return 0 when it matches, or a non-zero status when it does not.

function drop_tmp -a command exit_code
  # If the current directory is /tmp or a subdirectory, drop the command.
  if string match -rq '^/tmp($|/)' (pwd)
    return
  end

  return 1
end

After defining the function (e.g., in your config.fish or a functions file), register it:

set --append bob_drop_rules drop_tmp

⚠️ Be careful ⚠️ :
Rules run after every command, so avoid slow operations in rules.

🤝 Contributing and origin

This project is derived from Sponge. Contributions, bug reports, and pull requests are welcome.

©️ License

Originally distributed under the MIT License by Andrei Borisov (2020). Modifications by enklht (2025).

MIT